The present invention relates generally to the soldering of aluminum-containing workpieces, and more particularly to the flux-free soldering of such workpieces in a controlled atmosphere. In particular, the invention relates to a furnace for flux-free soldering of aluminum-containing workpieces in a controlled atmosphere, and a method of carrying out such soldering.
The conventional way of soldering aluminum workpieces and those which contain aluminum is to use flux of one of the well known types. It is known from the prior art to effect flux soldering of aluminum-containing workpieces in furnaces which are constructed as air-circulating furnaces. These furnaces must be largely constructed of ceramic materials because other materials are strongly attacked by the flux substances. Another approach from the prior art is to solder in metallic furnaces which do not require the use of ceramic materials, and wherein the soldering is carried out in a high vacuum. However, this type of furnace cannot be used for soldering without flux and under a protective gas atmosphere. The reason is that in this latter type of furnace, which must be heated by radiation, the outer wall is constructed as a water-cooled double wall against which heat radiation is directed. This principal cannot be used in furnaces using a protective gas atmosphere because otherwise the heated protective gas would predominantly yield its heat to the water-cooled wall of the furnace rather than to the workpieces.